LIBRO-CONGRESO-CITRUS

incidence of canker. Only in the year with 91% of incidence in untreated trees, a high dose of copper sprayed
in medium and low volumes significantly increased canker control, compared to the traditional high volume
treatment. The latter was in turn more effective than low dose sprayed in medium and low volumes.
S12P30
Control of Citrus Canker(Xanthomonas citri subsp. citri) mediated by neonicotinoids in
combination with acibenzolar-S-methyl and copper
Barreto T.P. 1 , Pozzan M. 2 , and Leite R. 1
1Instituto Agronomico do Parana (IAPAR), Area de Proteção de Plantas, Brazil; and 2Syngenta Proteção de Cultivares Ltda. (Syngenta),
Proteção de Cultivos, Brazil. ruileite@iapar.br
Asiatic Citrus Canker, caused by Xanthomonas citri subsp. citri, is a serious disease for commercial citrus
production. Multiple sprays of copper-based bactericides during the growth season are standard measure for
Citrus Canker control worldwide. Disadvantages for long-term use of copper bactericides include the selection
for copper resistance in Xanthomonas populations and accumulation of copper in the soil. Systemic acquires
resistance (SAR) is an innate plant defense that may confer long-lasting protection against a broad spectrum
of microorganisms. SAR may be activated by treatment of plants with chemical inducers. The purpose of this
research was to evaluate the efficacy of applications of SARs neonicotinoids in combination with acibenzolar-
S-methyl and copper oxychloride (COC) to control Citrus Canker. Plants of sweet orange ‘Pera’ (Citrus sinensis)
were treated by drench with neonicotinoid insecticides imidacloprid (IMI) and thiamethoxam (TMX), and
acibenzolar-S-methyl (ASM), and by foliar applications of ASM and COC. ASM and COC were applied during
the entire growth season, in a six-spray program. IMI and TMX were applied in the first and third sprays of
the six-spray program in an attempt to reduce early canker disease on foliage. ASM or TMX in combination
with COC were the most effective treatments to reduce Citrus Canker incidence on foliage as compared to the
untreated plants, COC alone and the other SARs treatments.
S12P31
Activity of antimicrobial peptides (AMPs) against Xanthomonas citri subsp. citri (Xcc) in Citrus
sinensis var. ´Baía´
Inui-Kishi R.N. 1 , Freitas-Astua J. 2 , Picchi S.C. 1 , Brand G.D. 3 , Bloch JR C. 3 , Falcao A.O. 4 , Stach-Machado D. 4 , Cilli E.M. 5 ,
and Machado M.A. 1
1Centro APTA Citros Sylvio Moreira (IAC), Laboratorio de Biotecnologia, Brazil; 2Embrapa Cassava and Fruits (EMBRAPA), Cruz das
Almas, Brazil; 3EMBRAPA CENARGEM (EMBRAPA), Brazil; 4Universidade Estadual De Campinas (UNICAMP), Biologia, Brazil; and
5Universidade Estadual Paulista Julio De Mesquita Filho (UNESP-ARARAQUARA), Departamento de Bioquimica e Tecnologia Quimica,
Brazil. rosangela@centrodecitricultura.br
The control of plant pathogens such as Xcc requires continuous use of chemicals, favoring the selection of
resistant isolates and increasing the risk of contamination to different organisms and environment. Thus,
it becomes important to search for feasible alternatives as AMPs. The aim of this study was to evaluate
the activity of six potential AMPs found within the citrus genome, as well as in other organisms, in the
control of Xcc. The in vitro growth inhibition of Xcc by the peptides was determined by MIC and MBC.
The pC1 obtained from citrus efficiently controlled Xcc at 64 µg mL-1, while the MIC values for peptides
pH2, pH3 and pH4 were 16, 4 and 8 µg mL-1 respectively. Experiments using detached C. sinensis leaves
were conducted with the same conditions used for the in vitro tests. For these experiments, a strain of Xcc
marked with GFP was used. The fluorescence obtained by GFP allowed monitoring the development of the
bacteria within the leaves. To confirm if it is able to control bacteria growth, CFU/mL from lesion leaf was
determined. The inhibition of Xcc growth was observed by five of the six peptides evaluated. Hemolysis
activity from the selected peptides was determined as the main measurement of peptide toxicity toward
higher eukaryotic cells. pC1 showed low percentage of hemolysis, while pH1, pH3 and pH4 exhibited higher
hemolysis levels. Five of the peptides tested show clear effect on Xcc, and the pC1 obtained from citrus
could be an interesting candidate.
XII INTERNATIONAL CITRUS CONGRESS 2012 - 211
S12